The average structure of organic substances contained in Barzas coal has been constructed by means of a commercial molecular modelling package on the basis of kinetic investigations and structural group analysis of high-molecular products obtained by the process of coal non-isothermal liquefaction in a proton–donor solvent. This model structure has been optimized geometrically by minimization of its conformational energy. The established model structure corresponds to the mean formula C 727H 790N 2S 4O 36 and to a molecular weight of 10,260 g/mol (amu).